Let us consider the two opposing poles of a magnet or an electromagnet. Except near the rim of the poles the magnetic field between the poles can be considered to be relatively homogeneous and unidirectional. In the prior art, the shape and intensity of such a field between poles could be manipulated only by the introduction of ferromagnetic materials as extensions of the poles, and the final shape of the field would be a strong function of the morphology of these add on pieces. This required that for each new configuration a different set of pole extensions with appropriate geometries be designed and mounted on the magnet poles. If the magnet was an electromagnet some control of the field intensity (but not shape) could be achieved by passing more or less current through the windings of the electromagnet. This could be achieved either by controlling the current through the windings (continuous change) or by using a number of independently powered coils and choosing the number of coils powered simultaneously to increase or decrease the field intensity (discrete change).
In a co-pending application entitled "Electronic Modulation of Magnetic Fields" I have described the principles of using switchable superconducting inserts in the geometry of existing magnetic fields to modify the flux distribution of the magnetic field in the vicinity of said inserts. In another co-pending application entitled "Switchable Superconducting Elements and Pixels Arrays" I have described how in an array of superconducting elements (supels) we can selectively switch into the normal phase any set of supels to create a desired pattern in which some of the supels are in the normal state and some are superconducting.
In the present invention similar devices and methods are used to obtain concentration and diffusion of existing magnetic field flux between the poles of a fixed magnet or an electromagnet.
Such devices are very useful in the art of magnetic separation, particularly when repeated sweeping of a magnetic field toward a center is desired, or when repeated sweeping of a magnetic field to the edge of a field configuration is required.
In the medical field, such devices can be used to modulate magnetic field in MRI diagnostic systems. Such devices can also find uses in the art of localized drug delivery systems and particularly localized oncological chemotherapy as magnetic field barriers and drug concentrators when using paramagnetic or diamagnetic drug carriers as well as in specialized immunoassay techniques.
These devices can be operated with existing superconductor technology at cryogenic temperatures.
The devices are not intended to operate near the limits of magnetic field strength of the superconductors involved, therefore very high current density capabilities of the superconductor used are not a major prerequisite.